Door engine



P. M. GRIFFIN DOOR ENGINE Filed Nov. 12, 1921 Nov. 20, 1928.

A TTUR E V Patented Nov. 20, 1928.

UNITED STATES PATENT OFFICE.

PERCY M. GRIFFIN, OF ALBANY, NEW YORK, ASSIGNOR, BY MESN ASSIGNMENTS, TO

CONSOLIDATED CAR-HEATING COMPANY, INC., 0]? ALBANY, NEW YORK, A. (703- PORATION OF NEW YORK.

noon ENGINE.

Application filed November 12, 1921. Serial Ito 1514 691.

For a detailed description of the present form of my invention, reference may be had to the following specification and to the accompanying drawing forming a part thereof, wherein v Fig. 1 is a section of an engine cylinder showing my invention;

Fig. 2 is a modified form thereof I My invention relates to door engines of the pneumatic type and consists in certain devices for venting the doorclosing end of the cylinder so as to counteract any tendency to accumulate excess pressure in said cylinder, as may happen when the closing of the door is obstructed, while in the same construction I render it possible to'leave the pressure on the said closing end of the cylinder after the engine has fully closed the door. In the ordinary door engine the pressure is automatically cut oil' from the engine after the door is fully closed, the door being then maintained closed by some locking expedient, usually by allowing the rotating arm which connects the engine with the door to come into a condition of dead center when the door is cldsed. Then the door can not be opened until the said arm has been turned up out of the said dead center position by the restarting of the engine to open the dooror, in some cases, by-hand. It is important, however, in-

certain circumstances to avoid-such locking devices and in place thereof to keep the door closed by maintaining pressure on the closing end of the 'engine cylinder. In the latter case, anordinary relief valve on the said clos-' ing end of the cylinder is not desirable because it would not only limit the pressure which can accumulate'while the door is being closed, but would also act after the door had become closed and thereby allow air to blow oii and be wasted. In my present arrangement I provide a reliefvalve for the doorclosing end of the cylinder which is operative for its relief function only so long as the door is in the act of closing, but which is automatically locked when the door is fully closed so that pressure may thereafter be left on the said closing end of the cylinder for holding the door in its closed position.

Referring to the drawing, F in Fi 1 represents the door-closing end and K t e dooropening end of a standard form of door engine, which has a piston consisting of two heads connected by a rack E that serves to transmit the longitudinal movement of the piston to the door. These two cylinder ends areinterconnected by means of an external tube B. At the closing end (right hand of the drawing) the air enters tube B by means, of the duct G and at the opposite end it communicates with the closing cylinder K through a'spring-pressed ball check-Valve C adjustable by a screw D and thence through a second ball valve H held down by a plate spring J The usual operators valve wellknown in the art (not shown) will, when turned for door-closing, admit pressure to the closing end F through the port 9 shown at the bottom andsimultaneously open the corresponding port 9 on the opposite end to the atmosphere. That will cause the pistons and rack E to move to the left and operate the door towards closing position. If the door should become blocked, the pressure in F will rise, and, if not checked, would become equal to the reservoir pressure. Then, when the door is released, the accumulated air pressure would move it'violently, causing it to slam or do damage by hitting a person in its path. But such accumulation of pressure is prevented because the excess pressure will be relieved by means of the aforesaid by-pass to the door-opening end through the tube B and check-valves O and H to the atmosphere. Through this by-pass the surplus pressure blows over into the closing end K which is at this moment opened to exhaust. When, however, the door is closed the left hand piston has reached the end of its stroke and a stud M comes against plate spring J, thereby looking the check-valve H. Thereafter the prespress spring P so in the pistons and rack, as appears at N. The left hand end of this duct N is closed by a ball valve ,0 with an operating spring P which abuts at one end against a stem Q that is free to slide through the screw bushing T, the other end of said spring bearing against a follower W which'en ages said valve 0. The action in this case wi 1 be the same as in Fig. 1. The arrival of the piston at the end of its stroke will bring the stem Q against the adjustable stop Ron the end wall of the cylinder. That will cause the said stem Q, to comthat ball valve 0 can not open under the maintained high pressure in F while the 'dooris in closed position. That high pressure can therefore be utilized to keep the door in its closed position so long as the said pressure is maintained in F. Moreover, it is important that the valve O should only openin response to a very definite high pressure in chamber F while the dooris open to an degree and that its opening shouldhave a su den and pronounced pressure-reducing effect by allowing a large volume of air to ass. On the other hand it is equally important that the valve should reclose as soon as a slight and definite drop of pressure has 00- curred inthe duct of a ball valve like 0 is to give a gradual leak by moving very slightly from its seat with a slow reductionof pressure in F and, when;

once unseated, to resist a return to its seat, by reason of the air current flowing through and around the ball until a considerable drop of pressure takes place behind it. To overcome this difliculty, I provide a recess S in the wall of the duct N just in advance of the follower W which intervenes between spring P and the ball. This recess is conveniently formed by drilling a hole across the duct and closing it on oner side by the screw A. I also make the ort hall, larger than that in the stem (2,. By this means a predetermined pressure in the chamber F will force the ball 0 and the follower W back far enough to permit a free flow of air through the recess S into the spring chamber and thence out through the stem-Q, into chamber K, leaving, however, an excess pressure in the spring chamber which co-operates with the spring to prom tly reseat the valve when a small and definite drop of pressure has occurred in duct While I have thus far described my device as a means of relieving excess pressure in the door-closing pressure-chamber of the engine, its operation involves also a certain arran ement of the engine valves whereby, at t e time that the excess pressure is blowing off from chamber F into the door-opening chamber K there is maintained in association with the latter chamber means (about to be described) by which a. certain amount of back pressure is built up within said chamber for checking the movement of the piston. Said N. The natural tendency.

through which the air reaches the chamber K .is open to, exhaust, as heretofore stated, but the outflow during most of the stroke is "choked as will be hereafter explained. Consequently it is not only the spr ng also such back V chamber K. he existence of such back pressure is important and perhaps essential in the practical operation of my device. Thus referring to Fi 1 Xrepresents one of P which act sto reseat the valve 0 but ressure as may then exist in' the two air pipes of t e engine which may be considered as the pressure pipe, the other one 1 Y being at this time open to exhaust. With the parts positioned as shown in Figure 1, the

pressure will passfreely from pipe X, by way of a widely-adjusted needle-valve 7 to duct 11, and thence, through check valve 5 and port 9, to the door-closing chamber F. At the opposite end chamber K will at first be freely open to exhaust through ort 10*, check valve.

5 to pipe Y. But imme iately after the piston starts, the head in chamber K passes port 10 and during the remainder of the stroke the only outlet from chamber K to the atmosphere is by port 9, closely-adjusted needlevalve 8*, to duct 11, and thence to the atmosphere through the widely-adjusted needlevalve'7 and pipe Y. The outflow by that route is restricted by needle-valve 8, so that there exists a rising backressure'in chamber K at the time that the a oresaid relief valve 0 acts to limit the pressure in chamber F. Therefore the prevention of injury by a too violent action of the engine is due to the increase of the back pressure in chamber K as well as to the reduction of direct pressure in chamber F. I am therefore enabled to use a comparatively light and .delicate spring P, since it normally responds to the differential pressure of the two chambers K and F and such a spring can be readily locked as heretofore described to hold valve 0 to its seat after the back pressure in K has finally leaked out through restricted valve 8, while full pressure is maintained in F to hold the door closed. Any other suitable means such as a separate valve may be employed for shutting o the relief flow from chamber F after the engine has completed its stroke and pressure I in F is maintained, but I prefer for that purpose to lock the check valve as described. It

of valves 5, 5, 6, 6, 7 7, 8, 8, and diicts 9, 9510, 10, 11, ll 'is employed as in Figure 1, although not shown in detail. It is deemed sufficient to show the full details in Figure l and indicate the construction generally in Figure 2.

What I claim as new and desire to secure by Letters Patent is: 1. A door engine comprising a door closing c lmder, a door opening cylinder, pistons in the respective cylinders, means connejcting the pistons, a duct connecting the two cylinders so that excess pressure in the door closing cylinder may be conveyed to the other cylinder, means for exhausting said last mentioned cylinder, and means in said duct operated at the end of the door closing movement of the pistons to close said duct so that a holding pressure may be maintained upon the piston in the door closing cylinder.

2. A door engine comprising a door closing cylinder, at door opening cylinder, pistons in the respective cylinders, means connecting the pistons so that they will move together, a duct connecting the two cylinders so that excess pressure in the door closing. cylinder may be conveyed to the other cylinder, means for exhausting said last mentioned cylinder,

means in said duct for controlling the pressure in the door closing cylinder, and means for disabling said pressure controlling means at the end of the door closing movement of the pistons so that a holding pressure may be maintained upon the piston in the door closing cylinder.

3. A door engine comprising a door closing cylinder, a door opening cylinder, pistons in the respective cylinders connected to move together, a duct connecting the two cylinders so that excess pressure in the door closingcylinder may be conveyed to the other cylinder,

means for exhausting said last mentioned'cylinder, a check valve in said duct normally unseated by'the pressure moving from the closing cylinder to the opening cylinder, and means actuated at the end of the door closing movement of said pistons to seat said valve so that a holding pressure may be maintained upon the piston in the door closing cylinder.

4. A door engine comprising a door closing cylinder, a door opening cylinder, pistons in the respective cylinders connected to move together, means connecting the two cylinders for controlling the pressure in one of them, means for exhausting said last mentioned cylinder, and means for disabling said pressure controlling means when 4 the pistons reach their limit of movement in one direction so that a holding pressure may be maintained upon the piston which operates in the other cylinder. v

5. A door engine comprising two cylinders, pistons working together, pressure limiting means connecting said cylinders so that excess pressure in one cylinder may be conveyed to the other cylinder, means for exhausting said last mentioned cylinder, and means cooperating with one of the pistons for disabling said limiting means when the piston reaches the limit of its movement in one direction so that 6. ,A door closing engine comprising connected piston heads, cylinders in which said piston heads are mounted to reciprocate, a duct connecting the two cylinders so that excess pressure in one ,cylinder may be conveyed "to the other cylinder, means for exhausting said last mentioned cylinder, a check valve in said duct for regulating the pressure in the first mentioned cylinder, and controlling means for said valve cooperating with the piston head in the other cylinder and operating at the end of the piston stroke in one direction to close said duct so that a hold ing pressure may be maintained upon the first mentioned piston head.

7. A door engine comprising two piston heads, a door operating rack connecting said heads, cylinders in which said heads are mounted to reciprocate, means providing a duct through said piston heads, said duct connecting the two cylinders so that excess pres sure in one cylinder may be conveyed to the other cylinder, means for exhausting said last mentioned cylinder, a check valve in' said duct, and means for holding said duct closed after the piston has completed its stroke in one direction, so that holding pressure may be maintained upon one of said pistons.

-8. A door engine comprising two pressure cylinders, a piston extending into both cylinders, a duct for relieving excess pressure in one of said cylinders, a spring pressed ball valve controlling said duct, said duct having a recess on the outlet side of the valve, so that said valve may be promptly reseat'ed after having been unseated, and a follower interposed between said valve and its spring and movable across said recess.

9. A door engine comprising two pressure cylinders, a piston provided with heads extending into the respective cylinders, means providing a duct for relieving excess pressure in one of said cylinders, a spring pressed ball valve controlling said duct and having an enlarged recess on the outlet side of the valve, the outlet of said recess having less capacity than the valve of the outlet so that the valve will readily reseat after having been unseated, and a follower interposed between the valve and its spring and movable across said recess. I Signed at Albany, .county of Albany and State of New York, this 9th day of November, 1921.

PERCY M. GRIFFIN. 

